2027 ICD-10-CM Diagnosis Code K61.1Rectal abscess

ICD-10-CM Codes›K00–K95›K55-K64›K61

ICD-10-CM K61.1
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

K61.1 is a billable ICD-10-CM diagnosis code for rectal abscess. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 393 through 395, 791, 793. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 7 closely related codes. Coders also document this condition as anorectal abscess. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Anal and rectal conditions and Peritonitis and intra-abdominal abscess.

Code Identity

ICD-10-CM Code
K61.1
Billable Status
Yes — Valid for Submission
Code Describes
Rectal abscess
Short Description
Rectal abscess
Same as the full description in the CMS dataset.
Parent Code
K61
Abscess of anal and rectal regions

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK55-K64Other diseases of intestines
CategoryK61Abscess of anal and rectal regions
This CodeK61.1Rectal abscess

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Anorectal abscess
  • Cellulitis - anus or rectum
  • Perirectal abscess
  • Perirectal cellulitis
  • Rectal abscess
  • Rectal cellulitis

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to K61.1: its own notes plus those printed at K61 and Chapter 11. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From K61 Abscess of anal and rectal regions applies to 7 codes
  • abscess of anal and rectal regions
  • cellulitis of anal and rectal regions

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Perirectal abscess

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 11 (K00-K95) Diseases of the digestive system applies to 863 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name K61.1, its category, or a range that includes it.

Excludes2 5

These codes carry an Excludes2 note naming K61.1: its condition is not part of those codes, and both may be reported when the patient has both.

  • K60 Fissure and fistula of anal and rectal regions
    abscess or cellulitis of anal and rectal regions (K61.-) names K61.-, which includes this code
  • K63.0 Abscess of intestine
    abscess of anal and rectal regions (K61.-) names K61.-, which includes this code
  • L02 Cutaneous abscess, furuncle and carbuncle
    abscess of anus and rectal regions (K61.-) names K61.-, which includes this code
  • L03 Cellulitis and acute lymphangitis
    cellulitis of anal and rectal region (K61.-) names K61.-, which includes this code
  • L03.31 Cellulitis of trunk
    cellulitis of anal and rectal regions (K61.-) names K61.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR DIG015
Anal and rectal conditions
Default principal diagnosis: inpatient No · outpatient No
CCSR DIG016
Peritonitis and intra-abdominal abscess
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Abscess

An abscess is a pocket of pus. You can get an abscess almost anywhere in your body. When an area of your body becomes infected, your body's immune system tries to fight the infection. White blood cells go to the infected area, collect within the damaged tissue, and cause inflammation. During this process, pus forms.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert K61.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
566 Anal & rectal abscess
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About K61.1Overview

What is the ICD-10 code for rectal abscess?

The ICD-10-CM code for rectal abscess is K61.1 (sometimes written as K611). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is K61.1 (Abscess of anal and rectal regions) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report rectal abscess on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does K61.1 group to?

When rectal abscess is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 394, 395, 393, with relative weights from 0.6379 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.

Is K61.1 a CC or MCC?

CMS lists K61.1 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 7 closely related codes in its exclusion list.

Can K61.1 be reported with K61.39?

Not as a rule. The Excludes1 note on K61.1 lists "ischiorectal abscess (K61.39)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).